This monoterpene, which shows so much promise for cancer treatment, is the same substance that gives lemon scent to furniture polish and grease-cutting power to detergent. (One scientist once described how it dissolved a researcher's plastic pipette.) It is found in citrus oils, as well as garlic and the oils of other plants; it is used in Japan to dissolve gallstones. Limonene and its chemical cousin, perillyl alcohol, show powerful anticancer effects in animals. In rats, limonene caused the complete regression of mammary tumors. Human studies are underway with cancer patients.